After reading the "instructions" that came with my new Accel replacement Distributor it finally hit me what vacuum advance is really for. So I decided to get on here to do some more in depth research. Before tonight I've been a VERY FIRM believer that the vac advance should be on ported vacuum. But now that I understand it's functionality I'll be switching it over to Manifold Vacuum and doin some retuning on the stock distributor tomarrow. My car has always been plagued with horrible gas mileage and now I know one of the reasons why.

I do have one question though. The new distributor came with all the different mechanical advance springs. But have yet to figure out how to best set the advance curve for my motor. The kit even includes a "tech card" which tells what the different springs "Curve start" and "Engine RPM Total" value's are. But I am unsure what all this means. If someone could point me towards an article or something explaining how to setup mechanical advance I'd greatly appreciate it. In this accel instructions it states to use lighter springs untill a ping is heard.. Then go back to the size before that and use the vacuum advance for fine tuning. This seems kind of shade tree to me...